Hitherto, dynamic change of resource assignment has been performed to optimize computer processing depending on the operating state of active application programs and the state of network traffic. For that purpose, the following techniques are proposed.
Japanese Unexamined Patent Application Publication Nos. 2005-174201 and 2007-48315 disclose a resource assignment change system that includes a resource list including a server, a network, and a storage; an application list showing the components of applications operating on the resources; an resource-application assignment list; a performance information measurement item template that generates performance information measurement items from the above configuration information; a performance measurement engine that measures the performance information measurement items; and means for generating resource assignment change rules used for changing resource assignment from the configuration information, wherein resource assignment is changed in accordance with the generated resource assignment change rules and the configuration information. The resource assignment change rules include threshold values of measured performance indices.
In order to provide an application execution system capable of stable system operation without being affected by server performance and line quality and without an additional space, Japanese Unexamined Patent Application Publication No. 2008-191737 discloses an application execution system in which a client terminal and an application execution unit are connected to a first network, and the application execution unit and a proxy server are connected to a second network, wherein the application execution unit includes an execution section that executes an application, and a switching section that operates independently of the execution section to transfer a received execution request to the execution section or the proxy server depending on the state of the execution section. The proxy server executes an alternative application in response to the execution request.
Although these prior arts disclose techniques for changing system configuration by changing performance on the server and improving the processing capacity depending on the result, they have a problem in that the system stops when the system configuration is changed.
Services based on cloud computing that many companies have recently introduced adopt the concept of service level agreement (SLA); if the system stop time is long, the service provider suffers a loss.
However, the related arts suggest no particular solution for reducing the system stop time during switching the system configuration.